An actuating device of the generic type (also referred to as a rotary drive), in which a drive piston executes an axial shift movement against the effect of at least one return spring in the case of a one-sided supply with a pressurizing medium, is described in EP 0 599 770 A2. In a tubular piston skirt releasably connected with the drive piston, two diametrically arranged axial grooves are arranged for the straight-line guide of the drive piston and a single cam guide groove tilted against the axial movement direction of the drive piston is arranged in order to generate the rotary movement of the drive shaft. The drive shaft is fed into the environment on one side through the floor of a housing of the actuating device, and a tubular bearing body is permanently arranged on this floor, which protrudes into the housing and serves to mount and guide the piston skirt on the end side. In the end-side area of the bearing casing facing away from the floor, a cross bolt is anchored in it, which radially penetrates the bearing casing from the one side to the other side and thereby reaches through the two axial grooves of the piston skirt. The drive shaft is radially mounted in the floor penetrated by it on one side and, in the direction towards its surrounding-area-side shaft end, axially mounted and, on the other side, it has its radial mounting on the inside of the tubular piston skirt, which is axially shiftable on the drive shaft. An axial mounting in the direction of the piston skirt has the drive shaft on the cross bolt. A radially oriented pin, which engages in the cam guide groove in the piston skirt, is permanently anchored in the drive shaft.
While the movement kinematics of the known actuating device is achieved with relatively simple means, it only works at the price of a hardly stable and imprecise drive-piston-side radial mounting of the drive shaft. This radial mounting takes place indirectly in the bearing casing, and namely via the tubular piston skirt, wherein the piston skirt itself is releasably connected with the drive piston and is joined with sufficient play respectively due to its axial back and forth movement radially outside with respect to the bearing casing and radially inside with respect to the drive shaft. Moreover, the rotation angle limitation of the drive shaft takes place in a stroke-dependent manner and thus imprecisely since the stroke movement of the drive piston or of the piston skirt connected with it is limited by unrevealed impacts and not the rotary movement.
FR 2 236 103 A1 describes a rotary drive with kinematics, which generally match those of EP 0 599 770 A2. However, the resetting of the drive piston does not take place through a return spring but rather it is supplied with pressurizing medium on both sides and the drive shaft is fed out of the housing of the rotary drive on both front sides of the housing.
An actuating device for a rotatable closure piece of a valve is described in DE 33 03 872 C2 or in its additional application (DE 33 15 244 A1). A single cam guide is provided in the piston of the former actuating device and two cam guides arranged opposite each other are provided in the piston of the latter device, which are worked into the outer piston casing in the form of diagonal grooves and engage in the drive rollers, which are rotatable around axes. The axes of the rollers are fastened on the housing casing of the actuating device. The piston thus executes a stroke and simultaneously a rotary movement in the case of a pressurizing medium supply. This rotary movement is transferred to a drive shaft connected with a valve shaft via a square coupling designed in the center of the piston. The drive shaft is overhung radially and axially to both sides in the lower cylinder cover of a tubular pneumatic cylinder and it thereby engages in a torque-proof, carrying manner in the piston axially shiftable on it. The rotation angle limitation of the drive shaft takes place in an axial idle position assumed by the piston under the effect of a return spring on an axially adjustable adjustment element. This thus involves a stroke-dependent and thus indirect rotation angle limitation.
DE 60 2004 001 988 T2 discloses an actuator for actuating a valve, which is provided with a rotatable valve element. A piston is exclusively axially shiftable against the reset force of a spring in a housing, since it is fed over respectively pairwise, diametrically arranged, housing-tight guide rods, which engage in the piston respectively axially and in the circumferential direction displaced against each other from both sides. Two cam guides arranged opposite each other in the form of helical, end-side respectively closed grooves are worked into the piston casing, into which drive rollers engage, which are rotatable around an axis permanently arranged in an actuating rod perpendicular to the longitudinal axis of the piston. The rotationally relocatable actuating rod is shiftably mounted in an axial and rotationally relocatable manner on one side in a cylindrical, centrical hole in the piston casing and it penetrates on the other side a floor of the housing and has there its axial fixed bearing. In the case of an axial shift of the piston, the actuating rod fixed axially in the housing floor thus executes an assigned rotary movement. The rotary movements are limited through placement of the drive rollers on the respectively assigned end of the groove.
DE 10 2010 002 621 A1 describes an actuator for a rotatable functional element, in particular a closure element of a disk valve or ball valve, which possesses the kinematic mode of operation of the actuator according to DE 60 2004 001 988 T2. In contrast to the latter, it possesses only two guide rods, wherein one is anchored in the one cover of a housing and the other in the other cover and the two guide rods in the piston end blindly in opposing directions. The rotation angle limitation of the drive shaft takes place through axial end position limitation of the piston on the covers. This thus involves a stroke-dependent and thus indirect rotation angle limitation.
An actuating device for a rotatable closure part of a valve, which possesses the kinematic mode of operation of the actuator according to DE 60 2004 001 988 T2 or DE 10 2010 002 621 A1, is described in DE 199 50 582 C1. In contrast to these two actuators, the actuating device has two housing-tight guide rods, which are arranged diametrically to each other in a cover of the housing and end blindly in the same direction in a shaft of the piston receiving the two helical grooves. The rotation angle limitation of the drive shaft takes place through axial end position limitation of the piston on the covers. This thus involves a stroke-dependent and thus indirect rotation angle limitation.
DE 28 17 260 A1 describes a setting device for fluid valves, for example a ball valve, in which an inner, hollow cylinder is mounted in a rotationally relocatable manner in a cylindrical outer housing, which has diametrically arranged, axially oriented slits. The inner cylinder possesses in its casing surface two diametrically arranged, helical grooves. A stroke cylinder arranged on the outer housing possesses a piston rod, which is led into the inner cylinder and engages there both in the grooves as well as in the slits with a cross pin permanently connected with the piston rod, on which sliding casings are arranged on both sides. The outer housing is permanently connected with a housing of the ball valve and the inner cylinder is permanently connected with a rotationally relocatable actuating rod of the ball valve. The piston rod guided in an axially mobile manner in the slits thus effectuates a rotary movement of the inner cylinder and thus of the actuating rod of the ball valve in the clockwise or counterclockwise direction in the case of a straight-line movement generated by the stroke cylinder. The rotation angle limitation of the inner cylinder takes place through axial end position limitation of the sliding casings on the closed ends of the axially oriented slit. This thus involves a stroke-dependent and thus indirect rotation angle limitation.
DE 43 13 751 A1 describes an actuating device for a rotatable closure piece of a valve, in which a casing-shaped appendage of a drive shaft guided out of a cover of the housing and mounted in a rotationally relocatable manner in an axial fixed bearing and said drive shaft protruding into a housing of the actuating device has two diametrically arranged helical grooves. Two diametrically arranged, axially oriented slits are provided in a bearing casing permanently connected with the cover. A piston rod of a shiftable piston arranged in the housing is permanently connected with a diagonal pin, on which two neighboring sliding rollers are arranged on both sides respectively. The respective outer sliding roller engages in the slit and the respective inner sliding roller engages in the groove. The piston rod guided in the slits in an axial mobile manner thus effectuates a rotary movement of the casing-shaped appendage and thus of the drive shaft in the case of a stroke movement generated by the piston. The rotation angle limitation of the drive shaft takes place on one hand through axial end position limitation of the piston on the other cover of the housing and on the other hand through placement of the sliding rollers on the closed ends of the slits. This thus involves a stroke-dependent and thus indirect rotation angle limitation.
DE 17 50 372 A discloses a four-way rotary slide changeover valve, in which a valve element or respectively a rotary slide can be turned between two operating positions. The required rotary movement is generated by means of a straight-line-working actuating device, which has two diametrically arranged cam guides on it circumference. An actuating pin arranged on a drive rod of the rotary slide engages into each of these cam guides. The two working positions of the rotary slide are fixed for example through a locking part fastened on the straight-line-working actuating device, which engages in an associated locking groove in the respective working position. This thus involves a stroke-dependent and thus indirect rotation angle limitation.
A flow-dependent, changeable rise in the cam guide groove of an actuating device of the type discussed here is described in EP 0 622 574 B1. This publication discloses a cam surface of the cam guide groove, which changes over to a more weakly bent and thus steeper cam section in the closed position of the disk valve, in the case of an only axially movable drive piston, which is guided in two housing-side straight-line guide grooves arranged diametrically to each other by means of drive rollers. Due to the weaker bend, an increase in the tangential force and thus an increase in the torque in this axial position of the drive piston and thus during movement of the closure part into the seating seal are achieved.
A stroke-independent, direct rotation angle limitation of the drive shaft is known from DE 20 2005 014 348 U1 and also from DE 297 03 710 U1. In the case of both rotary drives, the drive piston is guided in a torque-proof manner, and namely through two guide rods arranged diametrically to each other and permanently connected with a floor of a housing, which engage in assigned guide holes in the drive piston. DE 20 2005 014 348 U1 discloses a rotary movement device for limiting the rotary movement, which consists of a locking cam anchored in the housing and a stop element permanently connected with the drive shaft and having an approximately circular-segment-like recess, into which the locking cam engages and in which it can move relatively between two end-side stop surfaces on a circular-segment-shaped track. DE 297 03 710 U1 describes a stop segment fastened on the drive shaft in a correspondence with the guide rods fastened on the floor of the housing, which limit the angle of rotation in a stroke-independent manner and directly to its exact target value. The two known rotation angle limitations are relatively complex and the end position limitation of the drive shaft does not take place directly on the stationary housing, but rather indirectly via a locking cam or via two guide rods, wherein an adjustment of the angle of rotation can only take place by reworking the circular-segment-like recess on the stop element or respectively on the stop segment.
The object of the present invention is to create an actuating device of the generic type, which is constructed in a simple manner and at the same time has a high stability in the area of the mount of the drive shaft and in the area of the straight-line and cam guide arranged in the drive piston and also has a stroke-independent, direct rotation angle limitation with the greatest possible accuracy.